Tilt cab power stream and valve control therefor
A hydraulic system and latching mechanism for a cab tiltably mounted to the chassis of a vehicle. The cab is normally disposed over the engine of the vehicle and is pivotally attached to the chassis at its forward end for movement through 90.degree.. The cab is powered by an air-motor-actuated hydraulic pump which energizes lifting cylinders disposed between the chassis and cab. When the system is energized, a hydraulically actuated latch is released prior to commencement of the tilting movement of the cab. A direction-control valve is employed which, when in the neutral or closed position, utilizes the pressures generated in the hydraulic system by the weight of the tilted cab in certain positions to assist the valve in sealing the reservoir port in the valve against leakage thereby preventing the cab from creeping.
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2. The vehicle of claim 1 wherein manual over-ride pumping means is provided to supply pressurized fluid to said cylinder in the event of a failure in said hydraulic motor or said pneumatic motor.
3. The vehicle of claim 1 and including a second piston and cylinder assembly communicated to said first conduit means, said piston and cylinder assemblies being disposed on opposite sides of said cab.
4. The vehicle of claim 1 wherein said first valve is a four-way, three-position valve.
5. The vehicle of claim 4 wherein said first valve is a rotary valve and comprises a housing having a longitudinally extending bore, a rotatable cylindrical valve core snugly received in said bore for rotation about its longitudinal axis therein, reservoir and a pair of cylinder port means in said housing, one of said cylinder port means being diametrically opposed to said reservoir port means, pressure port means in said housing said second conduit means comprising an output conduit between said valve and said pump and a return conduit between said reservoir, said pressure port means being connected to said output conduit, said return conduit to said reservoir port means and said one cylinder port means to said first passageway means, passageway means in said valve core for alignment with said ports whereby by rotating said core said cylinder port may be selectively communicated to either said pressure port means or said reservoir port means, and said valve having a neutral position wherein said passageway means is out of alignment and out of communication with each of said port means and wherein any back pressure exerted in said first conduit means and through said one cylinder port means tends to urge said core against the opposite wall of said bore to seal the area surrounding said diametrically opposed reservoir port.
6. A latch system for a motor vehicle having an elongated chassis, a cab, means pivotally mounting said cab on said chassis about an axis transverse to the longitudinal axis of said chassis, a double-acting fluid-pressure-actuated piston and cylinder assembly having one end connected to said chassis and the other end connected to said cab for moving said cab from a normally lowered position, to a partially raised, 45.degree. second position, and to a fully raised, 90.degree. forwardly tilted third position, said cab by the weight thereof urging said piston and cylinder to nest when between said first and second positions and to expand when between said second and third positions,
- a hydraulic pump,
- a fluid reservoir,
- a directional flow control valve,
- first conduit means communicating said cylinder to said valve, and
- second conduit means communicating said pump and said reservoir to said valve,
- latch means between said chassis and cab to lock said cab in said first position,
- third conduit means communicating said latch means to said first conduit means and said latch means movable from a normally closed position to an open position in response to a predetermined increase in pressure in said first conduit means,
- valve means in said third conduit means preventing return fluid flow from said latch means when said cab is in a tilted position, and
- actuator means.Iadd.activated.Iaddend.by said cab just prior to its reaching said first position to maintain said valve means in said third conduit means in the open position.
7. The system of claim 6 wherein said valve means in said third conduit means is a ball check valve and said actuator means is a plunger normally biased out of engagement with said ball but adapted to engage and unseat said ball upon being depressed by said cab as it nears the first or lowered position.
8. The system of claim 6 wherein safety means are provided to block fluid flow from said cylinder assembly upon a sensing of fluid flow faster than a preselected value.
9. The system of claim 6 and including a pneumatic motor for driving said hydraulic pump.
10. The system of claim 9 wherein a manual override pumping means is provided to supply pressurized fluid to said cylinder in the vent of a failure in said pneumatic motor..Iadd. 11. In a motor vehicle having an elongated chassis, a cab, means pivotally mounting said cab on said chassis about an axis transverse to the longitudinal axis of said chassis, at least one fluid-pressure-actuated piston and cylinder assembly having one end connected to said chassis and the other end connected to said cab for moving said cab from a normally lowered first position to a partially raised over-the-center second position, and to a fully raised forwardly tilted third position, said cab by the weight thereof urging said piston and cylinder to expand when between said second and third positions, latch means between said chassis and cab to lock said cab in said first position, a hydraulic pump, a fluid reservoir, a first flow control valve, first conduit means connecting said cylinder to said first valve, second conduit means connecting said pump and said reservoir to said first valve, the improvement comprising pulsating pneumatic motor means for driving said pump, said latch means being fluid pressure actuated, third conduit means communicating said latch means to said first conduit means, said latch means being movable from a normally closed position to an open position in response to a predetermined increase in pressure in said first conduit means, a second valve in said third conduit means preventing return fluid flow from said latch means when said cab is in a tilted position, and actuator means activated by said cab prior to its reaching said first position to maintain said second valve in an open position..Iaddend..Iadd. 12. The system of claim 11 wherein said second valve in said third conduit means is a ball check valve and said actuator means is a plunger normally biased out of engagement with said ball but adapted to engage and unseat said ball upon being depressed by said cab as it nears the first or lowered position..Iaddend..Iadd. 13. A latch system for motor vehicle having an elongated chassis, a cab, means pivotally mounting said cab on said chassis about an axis trasverse to the longitudinal axis of said chassis, at least one fluid-pressure-actuated piston and cylinder assembly having one end connected to said chassis and the other end connected to said cab for moving said cab from a normally lowered first position, to a partially raised over-the-center second position, and to a fully raised forwardly tilted third position, said cab by the weight thereof urging said piston and cylinder to nest when between said first and second positions and to expand when between said second and third positions:
- a hydraulic pump,
- a fluid reservoir,
- a fluid flow control valve,
- first conduit means communicating said cylinder to said valve, and
- second conduit means communicating said pump and said reservoir to said valve,
- latch means between said chassis and cab to lock said cab in said first position,
- third conduit means fluidically communicating said latch means to said first conduit means and said latch means movable from a normally closed position to an open position in response to a predetermined increase in pressure in said first conduit means,
- valve means fluidically connected to said third conduit means preventing return fluid flow from said latch means when said cab is in a tilted position, and actuator means activated by said cab just prior to its reaching said first position to maintain said valve means connected to
said third conduit means in the open position..Iaddend..Iadd. 14. The system of claim 13 wherein said valve means in said third conduit means is a ball check valve and said actuator means is a plunger normally biased out of engagement with said ball but adapted to engage and unseat said ball upon being depressed by said cab as it nears the first or lowered position..Iaddend..Iadd. 15. In a motor vehicle having an elongated chassis, a cab, means pivotally mounting said cab on said chassis about an axis transverse to the longitudinal axis of said chassis, at least one fluid pressure actuated piston and cylinder assembly having one end connected to said chassis and the other end connected to said cab for moving said cab from a normally lowered first position to at least a partially raised second position, said cab by the weight thereof urging said piston and cylinder together when said cab is in said second position, latch means between said chassis and cab to lock said cab in said first position, a hydraulic pump, a fluid reservoir, a first flow control valve, first conduit means connecting said at least one cylinder to said first valve, second conduit means connecting said pump and said reservoir to said first valve, means for driving said pump, said latch means being fluid pressure actuated, third conduit means communicating said latch means to said first conduit means, said latch means being movable from a normally closed position to an open position in response to a predetermined increase in pressure in said first conduit means, a second valve in said third conduit means preventing return flow from said latch means when said cab is in a tilted position and actuator means activated by said cab prior to its reaching said first position to maintain said second valve in an open position..Iaddend..Iadd. 16. The system of claim 15 wherein said second valve in said third conduit means is a ball check valve and said actuator means is a plunger normally biased out of engagement with said ball but adapted to engage and unseat said ball upon being depressed by said cab as it nears the first or lowered position.
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Type: Grant
Filed: Jul 6, 1977
Date of Patent: Mar 20, 1979
Assignee: Applied Power Inc. (Milwaukee, WI)
Inventor: Dale A. Knutson (Oconomowoc, WI)
Primary Examiner: Kenneth H. Betts
Attorneys: John J. Byrne, Edward E. Dyson
Application Number: 5/813,234
International Classification: B62D 3306;
